#define _CRT_SECURE_NO_WARNINGS 1

class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int ans = 0;
        for (int i = 0; i < 32; i++)
        {
            int sum = 0;
            for (int num : nums)
            {
                if ((num >> i) & 1)
                    sum++;
            }
            if (sum % 3 == 1) ans |= (1 << i);
        }
        return ans;
    }
};